what's it worth?

[skaz500]

my neighbor has an original 1976 gt 500 4200 mi excellent condition...
.new tires brakes plugs .what s a fair price?

[Alan H]

Whatever you can get it for!!

[Vintageman]

4200 miles is good but, it also means it sat still for most its life. The key is oxidation external and internal.

Internal for example, let’s say one cylinder was at or near top dead center or bottom when parked (very likely) . Near top the intake port is open to atmosphere via carb. Piston near bottom the transfer port is open to exhaust port is open to atmosphere via muffler. Next depends where the bike was stored.

Where I live you can have quick temperature changes and moisture in the atmosphere resulting in condensation/dew. In the scenarios above that moist air makes it into the ports and into the rod bearings. On two strokes the rod bearings are needle rollers not plain bearing for it is not a pressurized oiling system. There is a significant air gap between consecutive rollers and rod eye surface,

When the moisture in the air condenses it pools and under needle bearings on the gravity side and rusts rod surface over time like stripes.
You run it for a while and those soft rust spot are analogous to tooth decay and your teeth start chipping away fast as you begin to chew: dentist/new dentures are expensive.

Check the inside of the gas tank, Underside as well (rust in tank , bubbles in paint). Water sinks to bottom of tank and you know the story

You and use NADA.com as guide Be weary of “Excellent” condition.

But It just may be a beautiful bike stored well!

It depends how bad you want it and how much he or she owner has seen “American Pickers” TV show